1. Field of the Invention
The present invention relates to a sealed aqueous self cleaning rinse sump for aqueous spray washers and, more particularly, to a rinse sump using a water seal to safely pressurize the rinse sump to facilitate purifying the rinse water.
2. Discussion
Production of many electronic components, such as circuit boards and the like, often involves coating and etching processes to fabricate the circuit boards. The circuit boards are typically passed through a sealed aqueous, belt driven, spray washer to remove etching and coating materials and the like. Such material removal steps may be part of an intermediate process or may be part of a final, finishing process. Numerous other fabrication processes exist which may similarly require intermediate or final wash and rinse steps as part of the fabrication process.
In circuit board fabrication, a typical wash and rinse cycle involves placing the product to be washed and rinsed on a conveyor belt. The conveyor proceeds into a spray washer having a wash section and a rinse section. The parts are sprayed or otherwise subjected to a wash fluid which then drains back into the wash sump. Following the wash cycle, the conveyor moves the product to a rinse section where the parts are sprayed with a rinse water. Aqueous spray washers of the type described here require as clean a rinse water as possible. Maintaining a clean supply of rinse water proves challenging because many products passed through spray washers, particularly circuit boards and the like, leave behind metals, oils, and other components in the rinse water.
Existing systems for cleaning rinse water require significant expense and time to obtain the desired purity of the rinse water. Some rinse water purification systems utilize either or both filters and membranes in order to properly clean the rinse water to maintain a generally pure rinse water concentration to provide optimal cleaning. Filters sometimes do not sufficiently purify the rinse water in accordance with the application requirements. Such systems often require very fine filter elements and often necessitate use of reverse osmosis filter systems. Filtration systems of this type requires additional, expensive apparatus, operate much more slowly in terms of filtration time and system inactivity for performing maintenance, and require greater operator intervention to periodically change filters and membranes.
Other spray washer systems completely change the rinse water periodically in order to provide clean rinse water. These systems require post-processing of the rinse water, which may contain metals which are costly to remove. Such an approach may only be cost effective for users having access to in-house water treatment facilities. A further drawback of such a system is that the rinse water will not remain consistently pure, as newly added rinse water will be much cleaner than rinse water at the end of a life cycle.
Yet another approach to providing clean rinse water utilizes a distillation process in which the rinse water in the sump is vacuumed boiled and condensed. The condensed water returns to the sump, and the returned rinse water is generally clean, while the contaminants in the rinse water have been removed by falling to the bottom of the sump. The vacuum distillation process, however, is typically a batch process. An affordable batch process apparatus has a low volume capacity and requires significant time to filter the rinse water, resulting in excessive down time. The batch process also requires significant operator intervention.
Thus, it is an object of the present invention to provide a self-cleaning rinse sump for aqueous spray washers.
It is yet a further object of the present invention to provide a rinse sump for aqueous spray washers which continuously cleans the rinse water.
It is yet a further object of the present invention to provide a rinse sump for aqueous spray washer which minimizes required operator intervention, expedites purification, and minimizes cost.